Field of the Invention
The present invention relates to imaging apparatus and, more particularly, to stereo imaging apparatus.
Image intensifiers are used in a variety of applications. Night vision devices are used by the military to amplify or intensify available light to give the human eye the capability of viewing a scene which the unaided eye cannot see. Such night vision devices are also useful for surveillance by law enforcement officials. Image intensifiers have also found applications in underwater photography and in other areas where the amount of available light is insufficent for the desired purpose.
Various types of image intensifiers are commercially available. One type of image intensifier is available from Varo, Inc., Electron Devices Division. This image intensifier is comprised of a photocathode upon which low level light is directed. The photocathode converts the phosphor image into electrons. The electrons are accelerated toward a phosphor screen through a microchannel plate. As the electrons propagate through the microchannel plate, additional electrons are produced such that the image produced on the phosphor screen is of a higher intensity than the image focused upon the photocathode. Unfortunately, the images available on the phosphor screen are not stereo images. When stereo images are required, two image intensifiers are typically provided, one for the right channel and one for the left channel. Although an apparatus having two image intensifiers may be suitable in certain applications, the weight, bulk, and cost of such an apparatus clearly limit the applications where such an apparatus may be used.
A stereo imaging apparatus using a single image intensifier is disclosed in U.S. patent application Ser. No. 727,748 filed Apr. 26, 1985 and assigned to the same assignee as the present invention. Disclosed therein is an image intensifier having a color wheel. The color wheel is provided with flanges of different lengths which rotate with the color wheel to act, alternately and repetitively, as shutters for receiving and blocking radiaton from right and left channels. In this manner, the incident radiation is time multiplexed such that the image intensifier alternately amplifies the radiation corresponding to one channel and then the radiation corresponding to the other channel.